1. Field of the Invention
The present invention relates to an improvement of a corona discharging apparatus used in a charging apparatus or a transfer apparatus or a cleaning apparatus of an electrostatic photographic copying machine.
2. Description of the Prior Art
It is necessary to strictly set particularly the length of a thin wire used for corona discharging (that is to say, the electrifying width achieved by such thin wire) in a corona discharging apparatus. Thus, if the thin wire is too short (for example having a length equal to the width of the copying paper), both ends of the wire receive less than sufficient electric current, and thereby indistinct copying is achieved by both ends of the wire since the quantity of charging at the central part of the corona discharging apparatus inevitably is different from the opposite ends thereof. On the contrary, an excessively long thin wire leads to corona discharge even at parts at both ends not intended for copying, and as a result the toner is spattered over parts of the electrostatic photographic copying machine. The adherence of such spattered toner on, for example, the shield case of the corona discharging apparatus leads to various disadvantages such as a decrease in the effect of the electric discharge or the development of an abnormal electric discharge.
As described above, it is very important to set the length of thin wire, and thus such setting has been done at the stage of design and manufacture of the machine and thereby must be achieved very precisely. If the length of the thin wire is found to be unsuitable after assembling the fabricated corona dicharging apparatus on an electrostatic photographic copying machine, the design and manufacture of the length of the thin wire again must be carried out. This requires extra time and cost.